Academic self-efficacy has been shown to have a significant correlation to academic success in college students (Robbins et al., 2004). Additionally, research has indicated that academic success plays a large role in stress levels experienced by college students (Pedersen & Jodin, 2016). Social comparison has also been posited as a significant contributor to academic experiences as it has been correlated to both the goals students set and their perceived ability to achieve them (Carmona et al., 2008; Micari & Drane, 2011b). While research suggests that academic self-efficacy and social comparison both contribute to student experience, to our knowledge, no studies exist that explore the potential influence of social comparison on the relationship between academic self-efficacy and stress levels. Research has also reported inconsistent findings regarding the relationship between perceived stress and biomarkers of stress. This study was primarily aimed at exploring the possible moderating effect of social comparison on the relationship between academic self-efficacy and stress levels. The secondary goal was to clarify the relationship between perceived stress and biological levels of stress as measured by cortisol levels in undergraduate college students. Findings suggest that academic self-efficacy and social comparison are both highly correlated to one another and perceived stress; however, social comparison does not moderate the relationship between self-efficacy and perceived stress. The correlation between perceived and biological levels of stress was dependent on the formula by which the diurnal curve of cortisol was examined using area under the curve and was therefore inconsistently significant. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]